[Webkit-unassigned] [Bug 42264] Prepare YARR JIT for matching regexps with iterative parentheses

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=42264





--- Comment #5 from Gavin Barraclough <barraclough at apple.com>  2010-07-15 15:25:17 PST ---
Hi Peter,

I'm very sorry, but I'm afraid I don't think that this patch correctly addresses the issue at hand.  Having two code paths for allocation of local storage adds an undesirable and unnecessary additional complexity and maintenance overhead to the engine.

Either the strategy of using dynamic stack (or similar) allocation for individual atoms can provide performance matching that of using compile-time determined stack frames, or it cannot.  If the performance of a dynamic allocation based design can be made sufficient then we should use this for all regular expressions - having the code to calculate stack-frames is unnecessary complexity and overhead if it is not giving us anything, and should be removed.  That said, if the use of stack frames is beneficial there should be no need to exclude a subset of regular expressions from taking advantage of this.

But again, I would suggest you might want to look into the correctness issue before trying to resolve the performance problem.  My expectation is that any solution to this will only further accentuate the need for stack-frame to be calculated by the compiler.

cheers,
G.

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